Fertilizing flights and the like generally take off from temporary fields and use low flying altitudes. Such circumstances may lead to hazardous situations in which quick reduction of weight could prevent the accident. A centrifugal type of spreader unit is provided with a transport container and closing means at the lower end thereof as well as a centrifugal wheel with its driving device at the bottom. The material to be spread will have to pass through the blade passages of said wheel which passages, even with the closing means open, limit the draining rate. Prior known with a spreader, provided with mechanical transmission, is a pneumatic controlled emergency draining mechanism by means of which the spreader is removed from the container and dropped off the airplane, whereby the container discharges freely. On the other hand, for the spreaders operating with hydraulic transmission there has not been developed a corresponding, sufficiently simple draining mechanism and therefore the equipment used at present are not fitted with it.
The object of the invention is to improve flying safety by means of an appropriate, simple and reliable emergency draining mechanism which can be fitted to a hydraulic centrifugal spreader.